9/11 – 10 Years Later: Shanksville

A couple looks at the field in Shanksville, on Sept. 9, 2011, where United flight 93 crashed on Sept. 11, 2001. The US prepares to mark the tenth anniversary of the Sept.11, 2001 attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

A couple looks at the field in Shanksville, on Sept. 9, 2011, where United flight 93 crashed on Sept. 11, 2001. The US prepares to mark the tenth anniversary of the Sept. 11, 2001 attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

Courtney Peller (R), 14, Taylor Duffy (C) and Caitlin Rakowski, both 15, embrace as they look at the field in Shanksville, on Sept. 9, 2011, where United flight 93 crashed on Sept. 11, 2001. The US prepares to mark the tenth anniversary of the Sept. 11, 2001 attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

Courtney Peller (L), 14, Taylor Duffy (C) and Caitlin Rakowski, both 15, look at the field in Shanksville, on Sept. 9, 2011, where United flight 93 crashed on Sept. 11, 2001. The US prepares to mark the tenth anniversary of the Sept. 11, 2001 attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

A man waits for the start of the dedication of the Flight 93 memorial on Sept. 10, 2011 at the site where the United plane crashed in Shanksville, on Sept. 11, 2001. The memorial will be dedicated later in the day.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

A man and his son walk on Sept. 10, 2011 to the Flight 93 memorial at the site where the United plane crashed in Shanksville, on Sept. 11, 2001. The memorial will be dedicated later in the day.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

A man walks away after viewing the field in Shanksville, on Sept. 9, 2011, where United flight 93 crashed on Sept. 11, 2001. The US prepares to mark the tenth anniversary of the Sept. 11, 2001 attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

A US Park Ranger stands by the Flight 93 memorial on Sept. 10, 2011 at the site where the United plane crashed in Shanksville, on Sept. 11, 2001. The memorial will be dedicated later in the day.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

People look at panels explaining the events aboard United flight 93 at the temporary Flight 93 memorial near the field where it crashed in Shanksville, on Sept. 9, 2011, as the US prepares to mark the tenth anniversary of the Sept. 11, 2001 attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

People look at photos of the crew and passengers of United flight 93 at the temporary Flight 93 memorial in Shanksville, on Sept. 9, 2011, near the field where the plane crashed on Sept. 11, 2001. The US prepares to mark the tenth anniversary of the attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

People arrive on Sept. 10, 2011 to the Flight 93 memorial at the site where the United plane crashed in Shanksville, on Sept. 11, 2001.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm /AFP/Getty Images)

People look at the field in Shanksville, on Sept. 9, 2011, where United flight 93 crashed on Sept. 11, 2001. The US prepares to mark the tenth anniversary of the Sept. 11, 2001 attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

People walk away from the field where United flight 93 in Shanksville on Sept. 9, 2011, as the US prepares to mark the tenth anniversary of the Sept. 11, 2001 attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

A sign reading 'We Remember 9/11' is seen at the field in Shanksville, on Sept. 9, 2011, where United flight 93 crashed on Sept. 11, 2001. The US prepares to mark the tenth anniversary of the Sept. 11, 2001 attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

A man looks at wreaths near the field where United flight 93 crashed in Shanksville on Sept. 9, 2011, as the US prepares to mark the tenth anniversary of the Sept. 11, 2001 attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

Taylor Duffy (L), 15, and Courtney Peeler, 14, embrace as they view the field in Shanksville, on Sept. 9, 2011, where United flight 93 crashed on Sept. 11, 2001. The US prepares to mark the tenth anniversary of the Sept. 11, 2001 attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

US Vice President Joe Biden speaks during the dedication of the Flight 93 memorial in Shanksville, on Sept. 10, 2011. A long white stone wall bearing the names of those who struggled with Al-Qaeda terrorists on the fourth airliner to be hijacked on Sept. 11, 2001 was unveiled on the rural Pennsylvania field where the Boeing 757 crashed.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

Former US President George W. Bush attends at the dedication of the Flight 93 memorial in Shanksville, on Sept. 10, 2011. A long white stone wall bearing the names of those who struggled with Al-Qaeda terrorists on the fourth airliner to be hijacked on Sept. 11, 2001 was unveiled on the rural Pennsylvania field where the Boeing 757 crashed.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

Former US president George W. Bush (C) and Vice President Joe Biden (L) greet family members of victims of United flight 93 during the dedication of the Flight 93 memorial in Shanksville, on Sept. 10, 2011. A long white stone wall bearing the names of those who struggled with Al-Qaeda terrorists on the fourth airliner to be hijacked on Sept. 11, 2001 was unveiled on the rural Pennsylvania field where the Boeing 757 crashed.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

Former US President George W. Bush speaks during the dedication of the Flight 93 memorial in Shanksville, Pennsylvania, on Sept. 10, 2011. A long white stone wall bearing the names of those who struggled with Al-Qaeda terrorists on the fourth airliner to be hijacked on Sept. 11, 2001 was unveiled on the rural Pennsylvania field where the Boeing 757 crashed.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

Former US President Bill Clinton (R) US former First Lady Laura Bush (C) and former President George W. Bush applaud during the dedication of the Flight 93 memorial in Shanksville, on Sept. 10, 2011. A long white stone wall bearing the names of those who struggled with Al-Qaeda terrorists on the fourth airliner to be hijacked on Sept. 11, 2001 was unveiled on the rural Pennsylvania field where the Boeing 757 crashed.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

Former US President Bill Clinton speaks during the dedication of the Flight 93 memorial in Shanksville, on Sept. 10, 2011. A long white stone wall bearing the names of those who struggled with Al-Qaeda terrorists on the fourth airliner to be hijacked on Sept. 11, 2001 was unveiled on the rural Pennsylvania field where the Boeing 757 crashed.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

Former US Presidents Bill Clinton (R) and George W. Bush, with his wife Laura, walk past the Wall of Names during the dedication of the Flight 93 memorial in Shanksville, Pennsylvania, on September 10, 2011. A long white stone wall bearing the names of those who struggled with Al-Qaeda terrorists on the fourth airliner to be hijacked on September 11, 2001 was unveiled on the rural Pennsylvania field where the Boeing 757 crashed.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: NICHOLAS KAMM/AFP/Getty Images)

Singer Sarah McLachlan performs during the dedication of the Flight 93 memorial in Shanksville, on Sept. 10, 2011. A long white stone wall bearing the names of those who struggled with Al-Qaeda terrorists on the fourth airliner to be hijacked on Sept. 11, 2001 was unveiled on the rural Pennsylvania field where the Boeing 757 crashed.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: NICHOLAS KAMM/AFP/Getty Images)

A man holds a US flag as he attends the dedication of the Flight 93 memorial in Shanksville, on Sept. 10, 2011. A long white stone wall bearing the names of those who struggled with Al-Qaeda terrorists on the fourth airliner to be hijacked on Sept. 11, 2001 was unveiled on the rural Pennsylvania field where the Boeing 757 crashed.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: NICHOLAS KAMM/AFP/Getty Images)

Flags and mementos are placed in a niche in part of the newly dedicated Flight 93 memorial in Shanksville on Sept. 10, 2011. A long white stone wall bearing the names of those who struggled with Al-Qaeda terrorists on the fourth airliner to be hijacked on Sept. 11, 2001 was unveiled on the rural Pennsylvania field where the Boeing 757 crashed.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Jeff Swensen/Getty Images)

SHANKSVILLE, PA - SEPTEMBER 10: (L-R) Secretary of the Interior Ken Salazar, former U.S. President George W. Bush, former first lady Laura Bush, former U.S. President Bill Clinton, Jill Biden, and U.S. Vice President Joe Biden listen to the national anthem during the dedication ceremony for the Flight 93 National Memorial Sept. 10, 2011 in Shanksville. The memorial was formally dedicated as an estimated crowd of 5000 watched as the memorial wall was unveiled with the names of the 40 passengers on the plane that crashed on Sept. 11, 2001.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: NICHOLAS KAMM/AFP/Getty Images)

Flowers are placed on the section of the Wall of Names dedicated to Captain Jason Dahl at the newly dedicated Flight 93 memorial at the site where the United plane crashed, marked by the boulder in the background, in Shanksville, on Sept. 10, 2011 as the US prepares to mark the tenth anniversary of the Sept. 11, 2001 attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Jeff Swensen/Getty Images)

SHANKSVILLE, PA - SEPTEMBER 10: Family members of Sept. 11 victims visit the Flight 93 Memorial, Sept. 10, 2011 in Shanksville. The Flight 93 National Memorial was formally dedicated with Presidents George W. Bush and Bill Clinton, Vice President Joe Biden, Secretary of the Interior Ken Salazar, Speaker of the House John Boehner and members of Congress in attendance. An estimated crowd of 5,000 watched as the memorial wall was unveiled with the names of the 40 passengers on the plane that crashed on Sept. 11, 2001.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Jeff Swensen/Getty Images)

SHANKSVILLE, PA - SEPTEMBER 10: Flowers sit along the Wall of Names at the Flight 93 Memorial for the dedication ceremony, Sept. 10, 2011 in Shanksville. The Flight 93 National Memorial was formally dedicated with former Presidents George W. Bush and Bill Clinton, Vice President Joe Biden, Secretary of the Interior Ken Salazar, Speaker of the House John Boehner and members of Congress in attendance. An estimated crowd of 5,000 watched as the memorial wall was unveiled with the names of the 40 passengers on the plane that crashed on Sept. 11, 2001.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: NICHOLAS KAMM/AFP/Getty Images)

Flowers are placed at the Wall of Names at the newly dedicated Flight 93 memorial at the site where the United plane crashed in Shanksville, on Sept. 10, 2011 as the US prepares to mark the tenth anniversary of the Sept. 11, 2001 attacks.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

A woman displays a US flag with an inscription reading ' Our nation will eternally honor the heroes of Flight 93' as people listen to speakers during a ceremony marking the tenth anniversary of the September 11, 2001 attacks at the newly dedicated Flight 93 memorial where the hijacked airliner fell in Shanksville, Pensylvania, on September 11, 2011.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

A woman displays a US flag with an inscription reading ' Our nation will eternally honor the heroes of Flight 93' as people listen to speakers during a ceremony marking the tenth anniversary of the September 11, 2001 attacks at the newly dedicated Flight 93 memorial where the hijacked airliner fell in Shanksville, Pensylvania, on September 11, 2011.

Flight 93 National Memorial (U.S. National Park Service)

(Photo Credit: Nicholas Kamm/AFP/Getty Images)

People listen to speakers during a ceremony marking the tenth anniversary of the September 11, 2001 attacks at the newly dedicated Flight 93 memorial where the hijacked airliner fell in Shanksville, Pensylvania, on September 11, 2011.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

A US Park Ranger bows his head during a moment of silence for the victims of United flight 93 at a ceremony marking the 10th anniversary of the 9/11 attacks at the newly dedicated Flight 93 memorial in Shanksville, Pensylvania, on September 11, 2011.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

People arrive to attend on September 11, 2011 the 10th anniversary of the 9/11 attacks at the newly dedicated Flight 93 memorial at the site where the United plane crashed in Shanksville, Pennsylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit to Mandel Ngan/AFP/Getty Images)

US President Barack Obama lays a wreath September 11, 2011 during a commemoration ceremony at the Flight 93 National Memorial on the 10th anniversary of the 9/11 attacks in Shanksville, Pennsylvania. Obama paid tribute Sunday to 9/11 victims at an hour-long ceremony in a rural Pennsylvania field where one of four planes commandeered by Al-Qaeda crashed exactly 10 years ago.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Mandel Ngan/AFP/Getty Images)

US President Barack Obama and First Lady Michelle Obama lay a wreath at the Flight 93 National Memorial on September 11, 2011 during a commemoration ceremony on the 10th anniversary of the 9/11 attacks in Shanksville, Pennsylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Mandel Ngan/AFP/Getty Images)

US President Barack Obama and First Lady Michelle Obama walk hand in hand on September 11, 2011 as they visit the crash site after attending in a commemoration ceremony at the Flight 93 National Memorial on the 10th anniversary of the 9/11 attacks in Shanksville, Pennsylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: MANDEL NGAN/AFP/Getty Images)

US President Barack Obama lay a wreath during a commemoration ceremony at the Flight 93 National Memorial on the 10th anniversary of the 9/11 attacks in Shanksville, Pennsylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Mandel Ngan/AFP/Getty Images)

US President Barack Obama and First Lady Michelle Obama walk hand in hand on September 11, 2011 as they visit the crash site after attending in a commemoration ceremony at the Flight 93 National Memorial on the 10th anniversary of the 9/11 attacks in Shanksville, Pennsylvania.

Flight 92 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

US President Barack Obama and his wife Michelle arrive to lay a wreath at the Wall of Names on September 11, 2011 during a ceremony marking the tenth anniversary of the September 11, 2001 attacks at the newly dedicated Flight 93 Memorial in Shanksville, Pensylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

US President Barack Obama and his wife Michelle arrive to lay a wreath at the Wall of Names on September 11, 2011 during a ceremony marking the tenth anniversary of the September 11, 2001 attacks at the newly dedicated Flight 93 Memorial in Shanksville, Pensylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

US President Barack Obama and his wife Michelle arrive to lay a wreath at the Wall of Names on September 11, 2011 during a ceremony marking the tenth anniversary of the September 11, 2001 attacks at the newly dedicated Flight 93 Memorial in Shanksville, Pensylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Mandel Ngan/AFP/Getty Images)

US First Lady Michelle Obama (L) and President Barack Obama greet guests during a commemoration ceremony at the Flight 93 National Memorial on the 10th anniversary of the 9/11 attacks in Shanksville, Pennsylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Mandel Ngan/AFP/Getty Images)

US President Barack Obama greets attendees on September 11, 2011 during a commemoration ceremony at the Flight 93 National Memorial on the 10th anniversary of the 9/11 attacks in Shanksville, Pennsylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Mandel Ngan/AFP/Getty Images)

US President Barack Obama and First Lady Michelle Obama visit on September 11, 2011 the crash site after attending in a commemoration ceremony at the Flight 93 National Memorial on the 10th anniversary of the 9/11 attacks in Shanksville, Pennsylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

US President Barack Obama and his wife Michelle lay a wreath at the Wall of Names during a ceremony marking the tenth anniversary of the September 11, 2001 attacks at the newly dedicated Flight 93 memorial at the site where the United plane crashed, in Shanksville, Pensylvania, on September 11, 2011.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

US President Barack Obama and his wife Michelle lay a wreath at the Wall of Names during a ceremony marking the tenth anniversary of the September 11, 2001 attacks at the newly dedicated Flight 93 memorial at the site where the United plane crashed, in Shanksville, Pensylvania, on September 11, 2011.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: NIcholas Kamm/AFP/Getty Images)

US President Barack Obama and his wife Michelle arrive to lay a wreath at the Wall of Names during a ceremony marking the tenth anniversary of the September 11, 2001 attacks at the newly dedicated Flight 93 memorial at the site where the United plane crashed, in Shanksville, Pensylvania, on September 11, 2011.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Mandel Ngan/AFP/Getty Images)

US President Barack Obama and First Lady Michelle Obama pay their respects after laying a wreath during a commemoration ceremony at the Flight 93 National Memorial on the 10th anniversary of the 9/11 attacks in Shanksville, Pennsylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Mandel Ngan/AFP/Getty Images)

US President Barack Obama, with First Lady Michelle Obama, lays a wreath September 11, 2011 during a commemoration ceremony at the Flight 93 National Memorial on the 10th anniversary of the 9/11 attacks in Shanksville, Pennsylvania. Obama paid tribute Sunday to 9/11 victims at an hour-long ceremony in a rural Pennsylvania field where one of four planes commandeered by Al-Qaeda crashed exactly 10 years ago.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Mandel Ngan/AFP/Getty Images)

US President Barack Obama lays a wreath September 11, 2011 during a commemoration ceremony at the Flight 93 National Memorial on the 10th anniversary of the 9/11 attacks in Shanksville, Pennsylvania. Obama paid tribute Sunday to 9/11 victims at an hour-long ceremony in a rural Pennsylvania field where one of four planes commandeered by Al-Qaeda crashed exactly 10 years ago.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Mandel Ngan/AFP/Getty Images)

US President Barack Obama and First Lady Michelle Obama walk across a muddy field upon arrival by Marine One for a commemoration ceremony at the Flight 93 National Memorial on the 10th anniversary of the 9/11 attacks in Shanksville, Pennsylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

US President Barack Obama waves as he walks to greet attendees with his wife Michelle after laying a wreath at the Wall of Names during a ceremony marking the tenth anniversary of the September 11, 2001 attacks at the newly dedicated Flight 93 memorial at the site where the United plane crashed, in Shanksville, Pensylvania, on September 11, 2011.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

US President Barack Obama pays his respects with his wife Michelle after laying a wreath at the Wall of Names during a ceremony marking the tenth anniversary of the September 11, 2001 attacks at the newly dedicated Flight 93 memorial at the site where the United plane crashed, in Shanksville, Pensylvania, on September 11, 2011.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

US President Barack Obama, with US First Lady Michelle Obama, walks on September 11, 2011 to the site where United flight 93 crashed in a field in Shanksville, Pennsylvania. Obama laid a wreath at the Wall of Names during a ceremony marking the tenth anniversary of the September 11, 2001 attacks at the newly dedicated Flight 93 memorial.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

US President Barack Obama smiles as he greets attendees on September 11, 2011 after laying a wreath at the Wall of Names (background) at the newly dedicated Flight 93 memorial on the site where United flight 93 crashed in a field in Shanksville, Pennsylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

US President Barack Obama greets a boy sitting on his father's shoulders on September 11, 2011 after laying a wreath at the Wall of Names (background) at the newly dedicated Flight 93 memorial on the site where United flight 93 crashed in a field in Shanksville, Pennsylvania

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

US President Barack Obama, with US First Lady Michelle Obama, walks on September 11, 2011 to the site where United flight 93 crashed in a field in Shanksville, Pennsylvania. Obama laid a wreath at the Wall of Names during a ceremony marking the tenth anniversary of the September 11, 2001 attacks at the newly dedicated Flight 93 memorial.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

US President Barack Obama greets a family member of one of the victims aboard United flight 93 on September 11, 2011 after laying a wreath at the Wall of Names (background) at the newly dedicated Flight 93 memorial on the site where United flight 93 crashed in a field in Shanksville, Pennsylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: Nicholas Kamm/AFP/Getty Images)

US President Barack Obama and his wife Michelle greet family members of victims aboard United flight 93 on September 11, 2011 after laying a wreath at the Wall of Names at the newly dedicated Flight 93 memorial on the site where the plane crashed in a field in Shanksville, Pennsylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit should read NICHOLAS KAMM/AFP/Getty Images)

US President Barack Obama hugs a family member of one of the victims aboard United flight 93 on September 11, 2011 after laying a wreath at the Wall of Names (background) at the newly dedicated Flight 93 memorial on the site wherethe plane crashed in a field in Shanksville, Pennsylvania.

Flight 93 National Memorial (U.S. National Park Service)

(Photo credit: NIcholas Kamm/AFP/Getty Images)

US President Barack Obama puts on a ribbon reading 'We Remember' given to him by a family member of one of the victims aboard United flight 93 on September 11, 2011 after laying a wreath at the Wall of Names at the newly dedicated Flight 93 memorial on the site wherethe plane crashed in a field in Shanksville, Pennsylvania.